This invention relates to a method and apparatus for recording and detecting indicating signals, commonly referred to as "cue" signals on a record medium in recording and/or reproducing apparatus and, more particularly, wherein such cue signals are used to indicate the relative locations of particular information, such as ends of messages, instructions, and the like, recorded on a record medium.
In many recording/reproducing devices, such as dictation/transcription machines, it is desirable to provide indications of different types of information which is recorded on the record medium used with such machines. Typically, these indications have been categorized broadly as "letter" and "instruction" indications, referring to the relative location of the end of a letter and of a dictated instruction, respectively. Such indications generally are helpful to a transcriptionist in transcribing the information which a dictator has recorded. In earlier machines, such indications are provided by suitable marks which are scribed on an index scale as the dictator is recording his message. Of course, when the record medium is loaded into a transcribing machine for transcription of the dictated messages, the prepared index scale also must be loaded into that machine so as to apprise the operator of the relative locations of the "letters" and "instructions" which have been recorded.
A marked improvement to the use of such scribed index scales for indicating the locations of ends of letters and instructions has been developed, whereby "letter" and "instruction" signals are electronically recorded on the very same record medium upon which the dictated messages are recorded. These signals, commonly referred to as "cue" signals, are of a predetermined frequency and can be detected electronically by suitable devices in the dictation/transcription machine prior to the transcription of the dictated information. One such system is disclosed in U.S. Pat. No. 4,051,540, wherein visual indicators, such as light emitting diodes (LED's) are selectively energized to provide appropriate indications of the locations of such recorded cue signals. An improvement to this system is disclosed in U.S. Pat. No. 4,200,893, wherein the visual indicators are controlled by a microprocessor.
In the electronic indicator systems disclosed in the aforenoted patents, particular electronic circuits are utilized to record and detect the cue signals. Typically, a recorded cue signal is formed of a burst of an oscillating tone of predetermined frequency. The burst is of a predetermined duration. When the record medium is driven at relatively high speeds in either the forward or reverse direction, the recorded bursts of cue signals are detected and indicated.
In some dictation/transcription machines in which cue signals are recorded, the very same burst of cue signal is used to indicate the location of an end of letter and of an instruction. If a so-called "letter cue" cannot be distinguished from a so-called "instruction cue", the transcriptionist may not easily discern the whereabouts of such information, thus complicating the transcription of the recorded information. Accordingly, it has been proposed that separate letter and instruction cue signals be recorded. In one such proposal, these different types of cue signals are recorded with different frequencies. However, this adds to the complexity of the cue signal recording and detecting circuitry, thus adding to the overall cost of the dictation/transcription machine. In accordance with another proposal, it has been suggested that separate tracks be dedicated for the recording of the letter and instruction cue signals, respectively. This, however, reduces the amount of record medium which is available for recording useful information, such as the dictator's messages.
It is one advantageous feature of the present invention to record separately distinguishable letter and instruction cue signals which overcome the aforenoted disadvantages.
With the advent of the microprocessor, various switching and control functions which heretofore have been carried out by discrete circuitry, electro-mechanical switching devices, and the like, now can be carried out under microprocessor control. By substituting a single microprocessor for multiple circuits and switching devices, the overall cost of the equipment which contains that microprocessor has been reduced and, moreover, reliability is improved. In accordance with yet another advantageous feature of the present invention, a microprocessor is used in a dictation/transcription machine to control the operation thereof as selected by the dictator or transcriptionist in accordance with his actuation of various control switches. The capacity of this microprocessor is sufficiently adequate such that it also is used to control the recording and detection of the aforementioned letter and instruction cue signals.